Process for preparing 1,6-hexanediol

ABSTRACT

Disclosed are processes for preparing 1,6-hexanediol from levoglucosenone. In one embodiment, the process comprises contacting levoglucosenone with hydrogen in the presence of a hydrogenation catalyst comprising palladium, platinum/tungsten, nickel/tungsten, rhodium/rhenium, or mixtures thereof at a first temperature between about 50° C. and 100° C. and at a first reaction pressure between about 50 psi and 2000 psi for a first reaction period, and at a second temperature between about 120° C. and 250° C. and at a second pressure between about 500 psi and 2000 psi for a second reaction period to form a product mixture comprising 1,6-hexanediol, wherein the first reaction period is the amount of time in which the levoglucosenone has a conversion of at least about 95%. In one embodiment, the 1,6-hexanediol is converted to 1,6-diaminohexane.

This application is a Continuation-In-Part of application Ser. No.13/729,494 filed Dec. 28, 2012.

FIELD OF DISCLOSURE

The present invention relates to processes for preparing 1,6-hexanediol,and to processes for converting it to 1,6-diaminohexane.

BACKGROUND

Industrial chemicals obtained from inexpensive sources are desirable foruse in industrial processes, for example as raw materials, solvents, orstarting materials. It has become increasingly desirable to obtainindustrial chemicals or their precursors from materials that are notonly inexpensive but also benign in the environment. Of particularinterest are materials which can be obtained from renewable sources,that is, materials that are produced by a biological activity such asplanting, farming, or harvesting. As used herein, the terms “renewable”and “biosourced” can be used interchangeably.

Biomass sources for such materials are becoming more attractiveeconomically versus petroleum-based ones. Although the convergent andselective synthesis of C₅ and C₆ carbocyclic intermediates from biomassis difficult because of the high degree of oxygenation of manycomponents of biomass, use of such biomass-derived intermediates asfeedstocks would offer new routes to industrially useful chemicals.

1,6-Hexanediol is a useful intermediate in the industrial preparation ofnylon. For example, 1,6-hexandiol can be converted by known methods to1,6-hexamethylene diamine, a useful monomer in nylon production.

There is an existing need for processes to produce 1,6-hexanediol, andsynthetic intermediates useful in the production of 1,6-hexanediol, fromrenewable biosources. There is an existing need for processes to produce1,6-hexanediol, as well as synthetic intermediates useful in theproduction of 1,6-hexanediol, from biomass-derived starting materials,including C₆ oxygenated hydrocarbons such as levoglucosenone. There isalso an existing need to produce 1,6-hexanediol from biomass-derivedstarting materials and to convert it to useful products such as1,6-diaminohexane.

SUMMARY

Disclosed herein are processes for converting levoglucosenone to1,6-hexanediol. In one embodiment, a process is disclosed, the processcomprising: contacting levoglucosenone with hydrogen in the presence ofa hydrogenation catalyst comprising palladium, platinum/tungsten,nickel/tungsten, rhodium/rhenium, or mixtures thereof at a firsttemperature between about 50° C. and 100° C. and at a first reactionpressure between about 50 psi and 2000 psi for a first reaction period,and at a second temperature between about 120° C. and 250° C. and at asecond reaction pressure between about 500 psi and 2000 psi for a secondreaction period to form a final product mixture comprising1,6-hexanediol, wherein the first reaction period is the amount of timein which the levoglucosenone has a conversion of at least about 95%.

In another embodiment of the process, the final product mixture furthercomprises 1,2,5,6-tetrahydroxyhexane or2-hydroxymethyl-5-hydroxytetrahydropyran, or both.

In some embodiments, the process comprises:

(a) contacting levoglucosenone with hydrogen in the presence of ahydrogenation catalyst comprising palladium, platinum/tungsten,nickel/tungsten, rhodium/rhenium, or mixtures thereof at a firsttemperature between about 50° C. and 100° C. and at a first reactionpressure between about 50 psi and 2000 psi for a first reaction period,wherein the first reaction period is the amount of time in which thelevoglucosenone has a conversion of at least about 95%; and at a secondtemperature between about 120° C. and 250° C. and at a second reactionpressure between about 500 psi and 2000 psi for a second reaction periodto form a final product mixture comprising 1,6-hexanediol;

(b) isolating the 1,6-hexanediol from the final product mixture;

(c) contacting the 1,6-hexanediol with ammonia and hydrogen in thepresence of a reductive amination catalyst at a temperature and for atime sufficient to form an amination product mixture comprising1,6-diaminohexane; and

(d) optionally, isolating the 1,6-diaminohexane from the aminationproduct mixture.

DETAILED DESCRIPTION

As used herein, where the indefinite article “a” or “an” is used withrespect to a statement or description of the presence of a step in aprocess disclosed herein, unless the statement or description explicitlyprovides to the contrary, the use of such indefinite article does notlimit the presence of the step in the process to one in number.

As used herein, when an amount, concentration, or other value orparameter is given as either a range, preferred range, or a list ofupper preferable values and lower preferable values, this is to beunderstood as specifically disclosing all ranges formed from any pair ofany upper range limit or preferred value and any lower range limit orpreferred value, regardless of whether ranges are separately disclosed.Where a range of numerical values is recited herein, unless otherwisestated, the range is intended to include the endpoints thereof, and allintegers and fractions within the range. It is not intended that thescope of the invention be limited to the specific values recited whendefining a range.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having,” “contains” or “containing,” or any othervariation thereof, are intended to cover a non-exclusive inclusion. Forexample, a composition, a mixture, process, method, article, orapparatus that comprises a list of elements is not necessarily limitedto only those elements but may include other elements not expresslylisted or inherent to such composition, mixture, process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

As used herein, the term “about” modifying the quantity of an ingredientor reactant employed refers to variation in the numerical quantity thatcan occur, for example, through typical measuring and liquid handlingprocedures used for making concentrates or use solutions in the realworld; through inadvertent error in these procedures; throughdifferences in the manufacture, source, or purity of the ingredientsemployed to make the compositions or carry out the methods; and thelike. The term “about” also encompasses amounts that differ due todifferent equilibrium conditions for a composition resulting from aparticular initial mixture. Whether or not modified by the term “about”,the claims include equivalents to the quantities. The term “about” maymean within 10% of the reported numerical value, preferably within 5% ofthe reported numerical value.

As used herein, the term “biomass” refers to any hemicellulosic orlignocellulosic material and includes materials comprisinghemicellulose, and optionally further comprising cellulose, lignin,starch, oligosaccharides and/or monosaccharides.

As used herein, the term “lignocellulosic” means comprising both ligninand cellulose. Lignocellulosic material may also comprise hemicellulose.In some embodiments, lignocellulosic material contains glucan and xylan.

Hemicellulose is a non-cellulosic polysaccharide found inlignocellulosic biomass. Hemicellulose is a branched heteropolymerconsisting of different sugar monomers. It typically comprises from 500to 3000 sugar monomeric units.

Lignin is a complex high molecular weight polymer and can compriseguaiacyl units as in softwood lignin, or a mixture of guaiacyl andsyringyl units as in hardwood lignin.

As used herein, the abbreviations “Lgone” and “LGone” refer tolevoglucosenone, also known as1,6-anhydro-3,4-dideoxy-p-D-pyranosen-2-one. The chemical structure oflevoglucosenone is represented by Formula (I).

As used herein, the abbreviations “Lgol” and “LGol” refer tolevoglucosanol, also known as 1,6-anhydro-3,4-dideoxyhexopyranose, andinclude a mixture of the threo and erythro stereoisomers. The chemicalstructure of 1,6-anhydro-3,4-dideoxyhexopyranose is represented byFormula (II).

As used herein, the abbreviation “K128” refers to1,6-anhydro-3,4-dideoxy-p-D-pyranose-2-one. The chemical structure of1,6-anhydro-3,4-dideoxy-p-D-pyranose-2-one is represented by Formula(III).

As used herein, the abbreviation “Tetraol” refers to1,2,5,6-tetrahydroxyhexane, also known as 3,4-dideoxyhexitol, andincludes a mixture of stereoisomers. The chemical structure of1,2,5,6-tetrahydroxyhexane is represented by Formula (IV).

As used herein, the abbreviation “THFDM” refers totetrahydro-2,5-furandimethanol, also known as2,5-bis[hydroxymethyl]tetrahydrofuran, and includes a mixture ofstereoisomers (cis- and racemic trans-isomers). The chemical structureof tetrahydro-2,5-furandimethanol is represented by Formula (V).

As used herein, the abbreviation “1,2,6-HT” refers to 1,2,6-hexanetrioland includes a racemic mixture of isomers. The chemical structure of1,2,6-hexanetriol is represented by Formula (VI).

As used herein, the abbreviation “THPM” refers totetrahydro-2H-pyran-2-methanol, also known as2-hydroxymethyltetrahydropyran, and includes a racemic mixture ofisomers. The chemical structure of tetrahydro-2H-pyran-2-methanol isrepresented by Formula (VII).

As used herein, the abbreviation “HOTHPM” refers to2-hydroxymethyl-5-hydroxytetrahydro-2H-pyran, also known as1,5-anhydro-3,4-dideoxyhexitol, and includes a mixture of stereoisomers.The chemical structure of 2-hydroxymethyl-5-hydroxytetrahydro-2H-pyranis represented by Formula (VIII).

As used herein, the abbreviation “1,6-HD” refers to 1,6-hexanediol. Thechemical structure of 1,6-hexanediol is represented by Formula (IX).

As used herein, the abbreviation “1,2-HD” refers to 1,2-hexanediol andincludes a racemic mixture of isomers. The chemical structure of1,2-hexanediol is represented by Formula (X).

As used herein, the abbreviation “1,2-CHD” refers to 1,2-cyclohexanedioland includes a mixture of stereoisomers (cis and racemic trans isomers).The chemical structure of 1,2-cyclohexanediol is represented by Formula(XI).

As used herein, the abbreviation “1,5-HD” refers to 1,5-hexanediol andincludes a racemic mixture of isomers. The chemical structure of1,5-hexanediol is represented by Formula (XII).

As used herein, the abbreviation “HexOH” refers to 1-hexanol. Thechemical structure 1-hexanol is represented by Formula (XIII).

As used herein, the abbreviation “PentOH” refers to 1-pentanol. Thechemical structure 1-pentanol is represented by Formula (XIV).

As used herein, the abbreviation “A128” refers to1,6-anhydro-3,4-dideoxy-β-erythro-hex-3-enopyranose, also known aslevoglucosenol. The chemical structure of A128 is represented by Formula(XV).

Disclosed herein are processes for obtaining 1,6-hexanediol, andsynthetic intermediates useful in the production of 1,6-hexanediol, fromlevoglucosenone, which in turn can be derived from a renewablebiosource. As used herein, the term “renewable biosource” includesbiomass and animal or vegetable fats or oils.

A renewable biosource can be pyrolyzed under high temperature conditionsin the presence of an acid catalyst to provide useful chemicalintermediates. For example, pyrolysis of wood, starch, glucose orcellulose can produce levoglucosenone by known and conventional methods(see, for example, Ponder (Applied Biochemistry and Biotechnology, Vol24/25, 41-41 (1990)) or Shafizadeh (Carbohydrate Research, 71, 169-191(1979)). In some embodiments, levoglucosenone as obtained by pyrolysisof biomass contains small amounts of acidic components, including formicacid, acetic acid, and levulinic acid.

In the processes disclosed herein, levoglucosenone is contacted withhydrogen in the presence of a hydrogenation catalyst comprisingpalladium, platinum/tungsten, nickel/tungsten, rhodium/rhenium, ormixtures thereof at a first temperature between about 50° C. and about100° C. and at a first reaction pressure between about 50 psi and 2000psi for a first reaction period, and at a second temperature betweenabout 120° C. and 250° C. and a second pressure between about 500 psiand 2000 psi for a second reaction period to form a final productmixture comprising 1,6-hexanediol. In some embodiments, the finalproduct mixture further comprises 1,2,5,6-tetrahydroxyhexane or2-hydroxymethyl-5-hydroxytetrahydropyran, or both.

For contacting with hydrogen in the presence of a hydrogenationcatalyst, the levoglucosenone is typically dissolved or suspended in aliquid medium, referred to herein as a “solvent”. Suitable solventsinclude water, a C₁-C₂₀ alcohol, a C₂-C₂₀ ether, a C₂-C₂₀ ester, ormixtures thereof. Examples of suitable alcohols which are commerciallyavailable include methanol, ethanol, propanol, butanol, and hexanol.Examples of suitable ethers which are commercially available includedibutylether, dihexylether, methyl-t-butyl-ether, tetrahydrofuran, anddioxane. Examples of suitable esters which are commercially availableinclude ethyl acetate, butyl acetate, methyl butyrate, ethyl butyrate,butyl butyrate and hexyl acetate.

The concentration of levoglucosenone in the solvent, whether dissolvedor as a suspension, is between about 1 wt % and about 50 wt %; in someembodiments it is between and optionally includes any two of thefollowing values: 1 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt %, 25 wt %, 30wt %, 35 wt %, 40 wt %, 45 wt %, and 50 wt %. It is anticipated thathigher concentrations of levoglucosenone in water, or even neatlevoglucosenone, could be used. The optimal concentration will depend onthe intended reaction conditions.

The levoglucosenone, hydrogenation catalyst, and hydrogen are contactedat a first temperature between about 50° C. and about 100° C., forexample between about 60° C. and about 90° C. In some embodiments, thefirst temperature is between and optionally includes any two of thefollowing values: 50° C., 60° C., 70° C., 80° C., 90° C., and 100° C.

The levoglucosenone, hydrogenation catalyst, and hydrogen are contactedat a first reaction pressure between about 50 psi and 2000 psi, forexample between about 200 psi and 1000 psi, or between about 500 psi and1500 psi. In some embodiments, the first reaction pressure is betweenand optionally includes any two of the following values: 50, 100, 200,300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500,1600, 1700, 1800, 1900, and 2000 psi. In some embodiments, the firstreaction pressure is between and optionally includes any two of thefollowing values: 200, 300, 400, 500, 600, 700, 800, 900, and 1000 psi.In some embodiments, the first reaction pressure is between andoptionally includes any two of the following values: 500, 600, 700, 800,900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, and2000 psi. Optionally, an inert gas can be used in combination with thehydrogen, with the proviso that the amount of any inert gas should besuch that it has no negative impact on the formation of the finalproduct mixture.

The levoglucosenone, hydrogenation catalyst, and hydrogen are contactedat a first temperature and at a first reaction pressure for a firstreaction period. The first reaction period is defined as the amount oftime in which the levoglucosenone has a conversion of at least about95%, that is, the amount of time sufficient to react at least about 95%of the sum of levoglucosenone and any1,6-anhydro-3,4-dideoxy-p-D-pyranose-2-one isomers and/or1,6-anhydro-3,4-dideoxy-β-erythro-hex-3-enopyranose isomers to one ormore chemical species, including levoglucosanol. The amount of timecorresponding to the first reaction period is determined by the specificreaction conditions selected, that is, the particular catalyst and itsamount relative to the levoglucosenone, the first and secondtemperatures, and the first and second pressures employed.

As the levoglucosenone is contacted with the hydrogenation catalyst andhydrogen at a first temperature and a first reaction pressure, anintermediate reaction mixture is formed. The intermediate reactionmixture comprises levoglucosenone reaction products, many of which areintermediates in the production of 1,6-hexanediol. The intermediatereaction mixture comprises one or more of levoglucosanol,1,2,5,6-tetrahydroxyhexane, 2-hydroxymethyl-5-hydroxytetrahydropyran,tetrahydrofuran-2,5-dimethanol, 1,2,6-hexanetriol, and2-hydroxymethyltetrahydropyran. The intermediate reaction mixture alsocomprises any unreacted levoglucosenone. In the processes disclosedherein, levoglucosanol may be produced and converted as a mixture ofstereoisomers (threo- and erythro isomer);tetrahydrofuran-2,5-dimethanol may be produced and converted as amixture of stereoisomers (cis- and trans isomer with respect to thehydroxymethy groups attached to the tetrahydrofuran ring: one cis mesocompound a trans racemate); 2-hydroxymethyltetrahydropyran may beproduced and converted as a racemate; 1,2,5,6-tetrahydroxyhexane may beproduced and converted as a mixture of stereoisomers differing only inthe configuration of the C2 and C5 carbon atom (one meso compound and aracemate); 1,2,6-hexanetriol may be produced and converted as racemate;and 2-hydroxymethyl-5-hydroxytetrahydropyran may be produced andconverted as a mixture of stereoisomers (two racemic stereoisomers).

When the first reaction period ends, that is, the levoglucosenone hasreached a conversion of at least about 95%, the intermediate reactionmixture is contacted with hydrogen in the presence of the hydrogenationcatalyst at a second temperature and at a second reaction pressure for asecond reaction period to form a final product mixture comprising1,6-hexanediol.

The second temperature is between about 120° C. and about 250° C., forexample between about 120° C. and about 180° C., or for example betweenabout 150° C. and about 230° C. In some embodiments, the secondtemperature is between and optionally includes any two of the followingvalues: 120° C., 130° C., 140° C., 150° C., 160° C., 170° C., 180° C.,190° C., 200° C., 210° C., 220° C., 230° C., 240° C., and 250° C. Insome embodiments, the second temperature is between and optionallyincludes any two of the following values: 120° C., 130° C., 140° C.,150° C., 160° C., 170° C., and 180° C. In some embodiments, the secondtemperature is between and optionally includes any two of the followingvalues: 150° C., 160° C., 170° C., 180° C., 190° C., 200° C., 210° C.,220° C., and 230° C.

The second reaction pressure is between about 500 psi and 2000 psi, forexample between about 500 psi and 1000 psi, or between about 500 psi and1500 psi. In some embodiments, the second reaction pressure is betweenand optionally includes any two of the following values: 500, 600, 700,800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900,and 2000 psi. In some embodiments, the second reaction pressure isbetween and optionally includes any two of the following values: 500,600, 700, 800, 900, and 1000 psi. In some embodiments, the secondreaction pressure is between and optionally includes any two of thefollowing values: 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400,and 1500 psi.

The second reaction period is the amount of time sufficient forformation of the final product mixture comprising 1,6-hexanediol. Higheryield of 1,6-hexanediol may be obtained with a longer second reactionperiod, as more of the intermediates are converted to 1,6-hexanediol. Insome embodiments, the final reaction product mixture further comprises1,2,5,6-tetrahydroxyhexane or 2-hydroxymethyl-5-hydroxytetrahydropyran,or both. In one embodiment, the final product mixture comprises1,6-hexanediol. In one embodiment, the final product mixture comprises1,6-hexanediol and 2-hydroxymethyl-5-hydroxytetrahydropyran. In oneembodiment, the final product mixture comprises 1,6-hexanediol,2-hydroxymethyl-5-hydroxytetrahydropyran, and1,2,5,6-tetrahydroxyhexane. In one embodiment, the final product mixturecomprises 1,6-hexanediol and 1,2,5,6-tetrahydroxyhexane.

At the end of the second reaction period, if desired, the hydrogenationcatalyst can be separated from the final product mixture by methodsknown in the art, for example by filtration. After separation from thecatalyst, if desired the product mixture components, including one ormore of 1,6-hexanediol, 2-hydroxymethyl-5-hydroxytetrahydropyran, and1,2,5,6-tetrahydroxyhexane, can be separated from one another using anyappropriate method known in the art, for example distillation.

The processes disclosed herein can be run in batch or continuous modes,in liquid phase, gas phase, or biphasic conditions. In a batch orcontinuous mode of operation, the amount of the hydrogenation catalystused will depend on the specific equipment configuration and reactionconditions.

Hydrogenation catalysts suitable for use in the disclosed processes arethose which are able to convert levoglucosenone in the presence ofhydrogen to a final product mixture comprising 1,6-hexanediol under thedisclosed reaction conditions. Suitable hydrogenation catalysts arethose which can effect conversion of at least about 95% of the sum oflevoglucosenone and any 1,6-anhydro-3,4-dideoxy-p-D-pyranose-2-oneisomers and/or 1,6-anhydro-3,4-dideoxy-β-erythro-hex-3-enopyranoseisomers to one or more chemical species, including levoglucosanol, at afirst reaction temperature between about 50° C. and 100° C. and at afirst reaction pressure between about 50 psi and 2000 psi, and then forma product mixture comprising 1,6-hexanediol at a second temperaturebetween about 120° C. and 250° C. and at a second reaction pressurebetween about 500 psi and 2000 psi.

In some embodiments, the hydrogenation catalyst comprises palladium,platinum/tungsten, nickel/tungsten, rhodium/rhenium, or mixturesthereof. Examples of suitable palladium catalysts include palladiumsupported on carbon. Examples of suitable nickel/tungsten catalystsinclude Ni/W/TiO₂ and Ni/W/Zeolite HY, which may be prepared asdescribed for Pt/W/TiO₂ in Example 1 using Ni(NO₃)₂ as a reagent. In oneembodiment, the hydrogenation catalyst comprises platinum/tungsten orrhodium/rhenium, optionally on a solid support. In one embodiment, thehydrogenation catalyst comprises platinum/tungsten supported on TiO₂,and the molar ratio of platinum to tungsten is in the range of 10:1 to1:10. In one embodiment, the hydrogenation catalyst comprisesrhodium/rhenium supported on silica, and the molar ratio of rhodium torhenium is in the range of 10:1 to 1:10.

In some embodiments, the hydrogenation catalyst comprises a metal M1 anda metal M2 or an oxide of M2, and optionally a solid support, wherein:

-   -   M1 is Pd, Pt, or Ir; and M2 is Mo, W, V, Mn, Re, Zr, Ni, Cu, Zn,        Cr, Ge, Sn, Ti, Au, or Co; or    -   M1 is Rh and M2 is Re, Mo, W, V, Mn, Ni, Cu, Zn, Cr, Ge, Sn, Ti,        Au, or Zr; or    -   M1 is Ag, Au or Co; and M2 is Re, Mo, or W;    -   M1 is Cu, Pd, Fe, or Ni; and M2 is Re, Mo, Cu, Zn, Cr, Ge, Sn,        or W; or    -   M1 is Ag, Pt, Cu, or Au, and M2 is Ni, Fe, Sn, Ge, or Ir; or    -   M1 is Co and M2 is Fe; or    -   M1 is N1 and M2 is Co or Fe; or    -   M1 is Mn and M2 is Cr.

The M1 and M2 components of the catalysts may be derived from anyappropriate metal compound. Examples include but are not limited to:rhodium (III) chloride hydrate, copper (II) nitrate hydrate, nickel (II)chloride hexahydrate, iridium (IV) chloride hydrate, iron (III) nitratenonahydrate, tetraammineplatinum (II) nitrate, platinum chloride,hexachloroplatinic acid, tetrachloroplatinic acid, palladium chloride,palladium nitrate, palladium acetate, iridium trichloride, ammoniumperrhenate, ammonium tungsten oxide hydrate, ammonium molybdate hydrate,manganese (II) nitrate hydrate, and ammonium vanadium oxide.

The loading of M1 may be 0.1-50% but preferably 0.5-5% by weight, basedon the weight of the prepared catalyst (i.e., including the solidcatalyst support where present). The loading of M2 may be 0.1-99.9%,preferably 2-10%. Preferably the atomic ratio of M1 to M2 in catalystscontaining both M1 and M2 is 1:0.5 to 1:5. Optionally, M2 may beincorporated into the catalyst support or serve as the catalyst support,e.g. Pt supported on tungsten oxide or molybdenum oxide. Regarding thecatalyst, all percentages are interpreted as weight percent relative tothe weight of the prepared catalyst.

In some embodiments, the hydrogenation catalyst comprises metals M1, M2,and M3 and optionally a support, wherein M1 is Mn, Cr, V, or Ti; M2 isNi, Co, or Fe; and M3 is Cu, Ag, Pt, Pd or Au; or M1 is Pt or Rh; M2 isCu, Ni or Pd; and M3 is Mo, Re or W.

In some embodiments, it is useful to utilize a solid catalyst support toenhance the stability and economic feasibility of the process. Examplesof supports include, without limitation: WO₃, SiO₂, Al₂O₃, carbon, TiO₂,ZrO₂, CeO₂, SiO₂—Al₂O₃, clays (e.g., montmorillonite), SiO₂—TiO₂,tungstated ZrO₂, aluminosilicates and zeolites (such as H—Y zeolite),V₂O₅, and MoO₃. In other embodiments, it may be desirable to not have asolid support.

The prepared hydrogenation catalyst can be in any physical form typicalfor heterogeneous catalysts, including but not limited to: powdered(also known as “fluidized”) forms with 0.01-150 μm particle size, formedtablets, extrudates, spheres, engineered particles having uniform 0.5-10mm size, monolithic structures on which surfaces the catalyst isapplied, or combinations of two or more of the above. When a solidsupport is utilized a catalyst containing both M1 and M2, it isdesirable that M1 be intimately associated with the M2 component, the M3component, or both, as measured by transmission electron microscopy withenergy dispersive spectroscopy. It is further preferable that theparticle size of the M1 component be less than 10 nm and most preferablyless than 3 nm as measured by the same techniques. In this case,particle size of the M1 component may be interpreted as particle size ofa mixture of the M1 and M2 components, an alloy of the M1 and M2components, a particle of the M1 component adjacent to a particle of theM2 component, or a particle of the M1 component on the support whichcontains the M2 component.

The hydrogenation catalysts can be synthesized by any conventionalmethod for preparing catalysts, for example, deposition of metal saltsfrom aqueous or organic solvent solutions via impregnation or incipientwetness, precipitation of an M1 component and/or an M2 component and/oran M3 component, or solid state synthesis. Preparation may comprisedrying catalyst materials under elevated temperatures from 30-250° C.,preferably 50-150° C.; calcination by heating in the presence of air attemperatures from 250-800° C., preferably 300-450° C.; and reduction inthe presence of hydrogen at 100-400° C., preferably 200-300° C., orreduction with alternative reducing agents such as hydrazine, formicacid or ammonium formate. The above techniques may be utilized withpowdered or formed particulate catalyst materials prepared by tableting,extrusion or other techniques common for catalyst synthesis. Wherepowdered catalysts materials are utilized, it will be appreciated thatthe catalyst support or the resulting catalyst material may be sieved toa desired particle size and that the particle size may be optimized toenhance catalyst performance.

The processes disclosed herein are advantageous in that only onecatalyst is needed for the conversion of levoglucosenone to1,6-hexanediol, thus avoiding any need to separate catalyst fromintermediate products or reaction mixtures. Additionally, the processesdisclosed herein provide routes to 1,6-hexanediol starting fromlevoglucosenone, which can be derived from biomass.

The 1,6-hexanediol obtained by the processes disclosed herein can beconverted to 1,6-diaminohexane, an industrially useful material. Forexample, 1,6-hexanediol can be reductively aminated to 1,6-hexanediamine(1,6-diaminohexane) by methods known in the art. See, for example, U.S.Pat. No. 3,215,742; U.S. Pat. No. 3,268,588; and U.S. Pat. No.3,270,059.

In some embodiments, the processes disclosed herein further comprise thesteps:

(b) isolating the 1,6-hexanediol from the final product mixture;

(c) contacting the 1,6-hexanediol with ammonia and hydrogen in thepresence of a reductive amination catalyst at a temperature and for atime sufficient to form an amination product mixture comprising1,6-diaminohexane; and

(d) optionally, isolating the 1,6-diaminohexane from the aminationproduct mixture.

The reductive amination catalyst contains at least one element selectedfrom Groups IB, VIB, VIIB, and VIII of the Periodic Table, for exampleiron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, copper,chromium, iridium, or platinum. The elements may be in the zerooxidation state or in the form of a chemical compound. The reductiveamination catalyst may be supported, unsupported or Raney-type. In oneembodiment, the reductive amination catalyst contains ruthenium. In oneembodiment, the reductive amination catalyst contains nickel. In oneembodiment, the reductive amination catalyst is Raney nickel. In oneembodiment, the reductive amination catalyst is Raney copper. In oneembodiment, the reductive amination catalyst is Raney cobalt.

The reductive amination step is conducted by contacting the1,6-hexanediol, or the final product mixture comprising the1,6-hexanediol, with ammonia and hydrogen in the presence of thecatalyst for a time sufficient to form an amination product mixturecomprising 1,6-diaminohexane. Useful temperatures for the reductiveamination step are in the range of about 40° C. to 300° C., for examplein the range of about 75° C. to 150° C. Typically pressures are in therange of about 2 MPa to 35 MPa, for example in the range of about 4 MPato 12 MPa. The molar ratio of hydrogen to the 1,6-hexanediol istypically equal to or greater than 1:1, for example in the range of 1:1to 100:1, or in the range of 1:1 to 50:1.

The reductive amination step is typically performed in liquid ammoniasolvent. The ammonia is used in stoichiometric excess with reference tothe 1,6-hexanediol. Typically, a molar ratio of 1:1 to 80:1 of ammoniato the 1,6-hexanediol can be used, for example a molar ratio in therange of 10:1 to 50:1. Optionally, an additional solvent such as water,methanol, ethanol, butanol, pentanol, hexanol, an, ester, a hydrocarbon,tetrahydrofuran, or dioxane, can be used. The weight ratio of theadditional solvent to the 1,6-hexanediol is typically in the range of0.1:1 to 5:1.

The reductive amination step can be performed in a fixed bed reactor orin a slurry reactor, for example a batch, continuous stirred tankreactor or bubble column reactor. The 1,6-diaminohexane may be isolatedfrom the second product mixture by any common methods known in the art,for example fractional distillation under moderate vacuum.

In some embodiments, the process comprises:

(a) contacting levoglucosenone with hydrogen in the presence of ahydrogenation catalyst comprising palladium, platinum/tungsten,nickel/tungsten, rhodium/rhenium, or mixtures thereof at a firsttemperature between about 50° C. and 100° C. and at a first reactionpressure between about 50 psi and 2000 psi for a first reaction period,wherein the first reaction period is the amount of time in which thelevoglucosenone has a conversion of at least about 95%; and at a secondtemperature between about 120° C. and 250° C. and at a second reactionpressure between about 500 psi and 2000 psi for a second reaction periodto form a final product mixture comprising 1,6-hexanediol;

(b) isolating the 1,6-hexanediol from the final product mixture;

(c) contacting the 1,6-hexanediol with ammonia and hydrogen in thepresence of a reductive amination catalyst at a temperature and for atime sufficient to form an amination product mixture comprising1,6-diaminohexane; and

(d) optionally, isolating the 1,6-diaminohexane from the aminationproduct mixture.

EXAMPLES

The methods disclosed herein are illustrated in the following examples.From the above discussion and these examples, one skilled in the art canascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various uses andconditions.

The following abbreviations are used in the examples: “° C.” meansdegrees Celsius; “wt %” means weight percent; “g” means gram; “min”means minute(s); “μL” means microliter; “wt %” means weight percent;“RV(s)” means reaction vessel(s); “PSI” means pounds per square inch;“mg/g” means milligram per gram; “μm” means micrometer; “mL” meansmilliliter; “mm” means millimeter and “mL/min” means milliliter perminute; “MPa” means megapascal; “GC” means gas chromatography; “MS”means “mass spectrometry”, “Temp” means temperature, “Ex” means Example.

All commercial reagents were used as received. All chemicals wereobtained from Sigma-Aldrich (St. Louis, Mo.) unless stated otherwise.Levoglucosenone (90% purity) was obtained from TimTec LLC (Newark,Del.).) 1,6-anhydro-3,4-dideoxy-p-D-pyranose-2-one (“K128”) and1,6-anhydro-3,4-dideoxy-β-erythro-hex-3-enopyranose (“A128”) wereprepared as described in Journal of Organic Chemistry, 63 (1998)8133-8144.

Reactor feeds and reaction products were analyzed by gas chromatographyusing standard GC and GC/MS equipment: Agilent 5975C, HP5890, StabilwaxColumn Restek Company Bellefonte, Pa. (30 m×025 mm 0.5 micron filmthickness). Chemical components of reaction product mixtures wereidentified by matching their retention times and mass spectra to thoseof authentic samples.

Synthesis of Pt/W/TiO_(z) catalyst

The Pt/W/TiO₂ catalyst was synthesized using the following procedure.0.92 Grams of Aerolyst 7708 TiO₂ (Evonik) that had been ground with amortar and pestle and passed through a 0.0165″ mesh sieve, then wettedwith 1.0 mL of deionized water, was impregnated with 0.08 g oftetraammineplatinum (II) nitrate (Strem, Cat #78-2010) dissolved in 1.0mL of deionized water. The resulting wet suspension was vortexed for 15minutes and then vacuum-dried at 110° C. overnight. The resultingprecipitate was wetted with 1.0 mL of deionized water, and then 0.0535 gof ammonium tungsten oxide hydrate (para analogue) (Alfa, stock #22640)which had been thoroughly dissolved in 2.0 mL of deionized water wasadded on to the wetted precipitate. The resulting wet suspension wasvortexed for 15 minutes and then vacuum-dried at 110° C. overnight.After reaching room temperature, the material was transferred to aceramic boat and calcined in air at 400° C. for three hours. Thecalcined Pt/W/TiO₂ catalyst had a Pt loading of 4 wt % based on thetotal weight of the catalyst, and a 1:1 molar ratio of Pt:W.

Synthesis of Rh/Re/SiO₂ Catalyst

The Rh/Re/SiO₂ catalyst was synthesized using the following procedure.1.795 Grams of SiO₂ (EMD, Cat. #9385-3) that had been ground with amortar and pestle and passed through a 0.0165″ mesh sieve, then wettedwith 2.0 mL of deionized water, was impregnated with 0.204 g of rhodium(III) chloride hydrate (Strem, Cat #45-1880) dissolved in 2.0 mL ofdeionized water. The resulting wet suspension was vortexed for 15minutes and then vacuum-dried at 110° C. overnight. The resultingprecipitate was wetted with 2.0 mL of deionized water, and then 0.094 gof ammonium perhenate (Aldrich, stock #316954) which had been thoroughlydissolved in 2.0 mL of deionized water was added on to the wettedprecipitate. The resulting wet suspension was vortexed for 15 minutesand then vacuum-dried at 110° C. for overnight. After reaching roomtemperature, the material was transferred to a ceramic boat and calcinedin air at 400° C. for three hours. The calcined Rh/Re/SiO₂ catalyst hada Rh loading of 4 wt % based on the total weight of the catalyst, and a1:0.5 molar ratio of Rh:Re.

Synthesis of Rh/Re/CBV78 Catalyst

Rh/Re/CBV780 was prepared following above procedure using the acidiczeolite “Zeolyst CBV780” (Zeolyst, CBV780, SiO₂/Al₂O₃ molar ratio: 80)as the support. The calcined Rh/Re/CBV780 catalyst had a Rh loading of 4wt % based on the total weight of the catalyst, and a 1:0.5 molar ratioof Rh:Re.

Example 1

Into a glass vial equipped with a magnetic stir bar were added 37.5 mgof levoglucosenone (˜90% pure), 0.75 mL of water, and about 50 mg of thePt/W/TiO₂ catalyst. The vial was capped with a perforated septum tolimit vapor transfer rates and placed in a stainless steel (SS316)parallel pressure reactor having 8 individual wells. Empty positionswere filled with water. The reactor was connected to a high pressure gasmanifold and the content was purged with nitrogen gas (1000 psi) threetimes before H₂ was added. About 800 psi of H₂ was added and the reactorwas heated to the first temperature, 60° C. After 2 h the firsttemperature was increased to the second temperature, 180° C., over thecourse of 30 min. After 4 h at 180° C. the reactor was allowed to coolto room temperature within 2 h and depressurized. The reaction solutionwas diluted with n-propanol and a known amount of diethylene glycoldiethyl ether as an internal standard, filtered through a standard 5micron disposable filter and analyzed by GC and GC/MS. Analysis of thereactor effluent is given in Table 1.

As can be seen from Table 1, the yield to 1,6-hexanediol was 62%. Thefinal product mixture also comprised2-hydroxymethyl-5-hydroxytetrahydropyran.

TABLE 1 Product Yields for Example 1 LGol THFDM HOTHPM THPM 1,6HD1,2,6HT 12HD HexOH m [mg] 3.9 0.4 0.6 2.6 20.8 2.1 1.0 3.2 n [mmol]0.030 0.003 0.005 0.022 0.176 0.015 0.009 0.031 Yield 10% 1% 2% 8% 62%5% 3% 11%

Examples 2-4

Examples 2, 3 and 4 were each performed according to the proceduredescribed below and demonstrate the conversion of levoglucosenone to afinal product mixture comprising 1,6-hexanediol. The catalysts, firsttemperatures, and second temperatures used are summarized in Table 2.

Into a 1.5 mL glass vial (ROBO Autosampler Vial available from VWRInternational, Radnor, Pa.) equipped with a magnetic stir bar were added37.5 mg of levoglucosenone, 0.75 mL water, and about 20 mg of catalyst.The vial was capped with a perforated septum to limit vapor transferrates and placed in a stainless steel (SS316) parallel pressure reactorhaving 8 individual wells. Any empty positions were filled with water.The reactor was connected to a high pressure gas manifold and thecontents were purged with nitrogen gas (1000 psi) three times. About1000 psi of H₂ was then added and the reactor was heated to the firsttemperature (Temp 1). After two hours the temperature was increased tothe second temperature (Temp 2) and the pressure was adjusted to 1100psi. The reactor was heated for another four hours. Subsequently, thereactor was allowed to cool to room temperature within two hours, andthe pressure was released. The reaction solution was diluted withn-propanol, filtered through a standard 5 micron disposable filter, andanalyzed by GC and GC/MS. Product distributions are given in Table 3.

TABLE 2 Catalysts and reaction conditions for Examples 2-4 ExampleCatalyst Temp1 Temp2 2 Rh/Re/SiO₂ 60 125 3 Rh/Re/CBV780 60 125 4Pt/W/TiO₂ 60 160

TABLE 3 Product Distributions (% mol, based on GC area % corrected usingrelative response factors) for Examples 3 through 5. 1,6- 1,2- 1,2,6-Other Ex LGone K128 LGol THFDM HOTHPM THPM HD CHD HT HexOH PentOHalcohols 3 <1 <1 <1 3 2 4 37 17 <1 14 4 18 4 <1 <1 <1 30 6 12 18 1 <1 11 30 5 <1 <1 <1 8 13 3 40 <1 32 <1 <1 2

What is claimed is:
 1. A process comprising: (a) contactinglevoglucosenone with hydrogen in the presence of a hydrogenationcatalyst comprising palladium, platinum/tungsten, nickel/tungsten,rhodium/rhenium, or mixtures thereof at a first temperature betweenabout 50° C. and 100° C. and at a first reaction pressure between about50 psi and 2000 psi for a first reaction period, wherein the firstreaction period is the amount of time in which the levoglucosenone has aconversion of at least about 95%; and at a second temperature betweenabout 120° C. and 250° C. and at a second reaction pressure betweenabout 500 psi and 2000 psi for a second reaction period to form a finalproduct mixture comprising 1,6-hexanediol; (b) isolating the1,6-hexanediol from the final product mixture; (c) contacting the1,6-hexanediol with ammonia and hydrogen in the presence of a reductiveamination catalyst at a temperature and for a time sufficient to form anamination product mixture comprising 1,6-diaminohexane; and (d)optionally, isolating the 1,6-diaminohexane from the amination productmixture.
 2. The process of claim 1, wherein the hydrogenation catalystfurther comprises a solid support selected from the group consisting ofcarbon, SiO₂, Al₂O₃, SiO₂—Al₂O₃, TiO₂, ZrO₂, CeO₂, WO₃, aluminosilicatesand zeolites.
 3. The process of claim 1, wherein the hydrogenationcatalyst comprises platinum/tungsten supported on TiO₂.
 4. The processof claim 3, wherein the molar ratio of platinum to tungsten is in therange of 10:1 to 1:10.
 5. The process of claim 1, wherein thehydrogenation catalyst comprises rhodium/rhenium supported on silica. 6.The process of claim 5, wherein the molar ratio of rhodium to rhenium isin the range of 10:1 to 1:10.
 7. The process of claim 1, wherein thefirst reaction pressure is between about 200 psi and 1000 psi.
 8. Theprocess of claim 1, wherein the reductive amination catalyst contains atleast one element selected from Groups IB, VIB, VIIB, and VIII of thePeriodic Table, for example iron, cobalt, nickel, ruthenium, rhodium,palladium, osmium, copper, chromium, iridium, or platinum.
 9. Theprocess of claim 1, wherein the reductive amination catalyst containsnickel.
 10. The process of claim 1, wherein the reductive aminationcatalyst is Raney nickel.
 11. The process of claim 1, wherein thereductive amination catalyst is Raney copper.
 12. The process of claim1, wherein the reductive amination catalyst is Raney cobalt.